Support of multiple SRS in the same subframe

ABSTRACT

Certain aspects of the present disclosure provide techniques for indicating capability of a user equipment (UE) to support multiple sounding reference signals (SRSs) with a single subframe, with at least one of frequency hopping, different bandwidths, or antenna switching for the multiple SRSs in the same subframe.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of and priority to U.S. ProvisionalPatent Application No. 62/971,193, filed Feb. 6, 2020, which is herebyincorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for indicating capability of a userequipment (UE) to support multiple sounding reference signals (SRSs)with a single subframe.

DESCRIPTION OF RELATED ART

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,broadcasts, etc. These wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, etc.). Examples of such multiple-access systems include3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)systems, LTE Advanced (LTE-A) systems, code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system mayinclude a number of base stations (BSs), which are each capable ofsimultaneously supporting communication for multiple communicationdevices, otherwise known as user equipments (UEs). In an LTE or LTE-Anetwork, a set of one or more base stations may define an eNodeB (eNB).In other examples (e.g., in a next generation, a new radio (NR), or 5Gnetwork), a wireless multiple access communication system may include anumber of distributed units (DUs) (e.g., edge units (EUs), edge nodes(ENs), radio heads (RHs), smart radio heads (SRHs), transmissionreception points (TRPs), etc.) in communication with a number of centralunits (CUs) (e.g., central nodes (CNs), access node controllers (ANCs),etc.), where a set of one or more distributed units, in communicationwith a central unit, may define an access node (e.g., which may bereferred to as a base station, 5G NB, next generation NodeB (gNB orgNodeB), TRP, etc.). A base station (BS) or distributed unit maycommunicate with a set of UEs on downlink (DL) channels (e.g., fortransmissions from a base station or to a UE) and uplink (UL) channels(e.g., for transmissions from a UE to a BS or DU).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. New Radio (NR) (e.g., 5^(th) generation(5G)) is an example of an emerging telecommunication standard. NR is aset of enhancements to the LTE mobile standard promulgated by 3GPP. Itis designed to better support mobile broadband Internet access byimproving spectral efficiency, lowering costs, improving services,making use of new spectrum, and better integrating with other openstandards using OFDMA with a cyclic prefix (CP) on a DL and on an UL. Tothese ends, NR supports beamforming, multiple-input multiple-output(MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in NR and LTEtechnology. Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improved anddesirable communications between a base station (BS) and a userequipment (UE) in a wireless network.

Certain aspects of the subject matter described in this disclosure canbe implemented in a method for wireless communications by a UE. Themethod generally includes reporting, to a network entity, capabilityinformation indicating a capability of the UE to support multiplesounding reference signals (SRSs) in a same subframe, wherein thecapability information includes one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe and transmitting the SRSs in accordance with thecapability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in a method for wireless communications by a networkentity. The method generally includes receiving, from a UE, capabilityinformation indicating a capability of the UE to support multiple SRSsin a same subframe, wherein the capability information includes one ormore parameters indicating capability of the UE to support at least oneof frequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe and configuring the UE fortransmitting the SRSs in accordance with the capability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in an apparatus for wireless communications by a UE. Theapparatus generally includes means for reporting, to a network entity,capability information indicating a capability of the UE to supportmultiple SRSs in a same subframe, wherein the capability informationincludes one or more parameters indicating capability of the UE tosupport at least one of frequency hopping, different bandwidths, orantenna switching for the multiple SRSs in the same subframe; and meansfor transmitting the SRSs in accordance with the capability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in an apparatus for wireless communications by a networkentity. The apparatus generally includes means for receiving, from a UE,capability information indicating a capability of the UE to supportmultiple SRSs in a same subframe, wherein the capability informationincludes one or more parameters indicating capability of the UE tosupport at least one of frequency hopping, different bandwidths, orantenna switching for the multiple SRSs in the same subframe; and meansfor configuring the UE for transmitting the SRSs in accordance with thecapability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in an apparatus for wireless communications by a UE. Theapparatus generally includes at least one processor and a memoryconfigured to report, to a network entity, capability informationindicating a capability of the UE to support multiple SRSs in a samesubframe, wherein the capability information includes one or moreparameters indicating capability of the UE to support at least one offrequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe; and transmit the SRSs in accordancewith the capability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in an apparatus for wireless communications by a networkentity. The apparatus generally includes at least one processor and amemory configured to receive, from a UE, capability informationindicating a capability of the UE to support multiple SRSs in a samesubframe, wherein the capability information includes one or moreparameters indicating capability of the UE to support at least one offrequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe; and configure the UE fortransmitting the SRSs in accordance with the capability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in a computer readable medium storing computer executablecode thereon for wireless communication by a UE. The computer readablemedium may include code for reporting, to a network entity, capabilityinformation indicating a capability of the UE to support multiple SRSsin a same subframe, wherein the capability information includes one ormore parameters indicating capability of the UE to support at least oneof frequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe; and code for transmitting the SRSsin accordance with the capability information.

Certain aspects of the subject matter described in this disclosure canbe implemented in a computer readable medium storing computer executablecode thereon for wireless communication by a network entity. Thecomputer readable medium may include code for receiving, from a UE,capability information indicating a capability of the UE to supportmultiple SRSs in a same subframe, wherein the capability informationincludes one or more parameters indicating capability of the UE tosupport at least one of frequency hopping, different bandwidths, orantenna switching for the multiple SRSs in the same subframe; and codefor configuring the UE for transmitting the SRSs in accordance with thecapability information.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe appended drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the drawings. It is to be noted, however, thatthe appended drawings illustrate only certain typical aspects of thisdisclosure and are therefore not to be considered limiting of its scope,for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram illustrating an example logical architectureof a distributed radio access network (RAN), in accordance with certainaspects of the present disclosure.

FIG. 3 is a diagram illustrating an example physical architecture of adistributed RAN, in accordance with certain aspects of the presentdisclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample base station (BS) and user equipment (UE), in accordance withcertain aspects of the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communicationprotocol stack, in accordance with certain aspects of the presentdisclosure.

FIG. 6 illustrates an example of a frame format for certain wirelesscommunication systems (e.g., new radio (NR)), in accordance with certainaspects of the present disclosure.

FIG. 7 illustrates an example of sounding reference signals (SRSs)transmissions with repetition, frequency hopping, and antenna switching,in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates an example of SRSs transmissions with frequencyhopping and antenna switching, but no repetition, in accordance withcertain aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating example operations for wirelesscommunications by a UE, in accordance with certain aspects of thepresent disclosure.

FIG. 10 is a flow diagram illustrating example operations for wirelesscommunications by a network entity, in accordance with certain aspectsof the present disclosure.

FIG. 11 illustrates examples of supported and unsupported SRSstransmission configurations for a given UE capability reported, inaccordance with certain aspects of the present disclosure.

FIG. 12 illustrates a communications device that may include variouscomponents configured to perform operations for techniques disclosedherein, according to aspects of the present disclosure.

FIG. 13 illustrates a communications device that may include variouscomponents configured to perform operations for techniques disclosedherein, according to aspects of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for indicating capability of a userequipment (UE) to support multiple sounding reference signals (SRSs)with a single subframe, with at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe.

The following description provides examples of supporting multiple SRSswith a same subframe, and is not limiting of the scope, applicability,or examples set forth in the claims. Changes may be made in the functionand arrangement of elements discussed without departing from the scopeof the disclosure. Various examples may omit, substitute, or add variousprocedures or components as appropriate. For instance, the methodsdescribed may be performed in an order different from that described,and various steps may be added, omitted, or combined. Also, featuresdescribed with respect to some examples may be combined in some otherexamples. For example, an apparatus may be implemented or a method maybe practiced using any number of the aspects set forth herein. Inaddition, the scope of the disclosure is intended to cover such anapparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to, or otherthan, the various aspects of the disclosure set forth herein. It shouldbe understood that any aspect of the disclosure disclosed herein may beembodied by one or more elements of a claim. The word “exemplary” isused herein to mean “serving as an example, instance, or illustration.”Any aspect described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other aspects.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a subcarrier, afrequency channel, a tone, a subband, etc. Each frequency may support asingle RAT in a given geographic area in order to avoid interferencebetween wireless networks of different RATs.

The techniques described herein may be used for various wirelesscommunication technologies, such as long term evolution (LTE), codedivision multiple access (CDMA), time division multiple access (TDMA),frequency division multiple access (FDMA), orthogonal frequency divisionmultiple access (OFDMA), single-carrier frequency division multipleaccess (SC-FDMA) and other networks. The terms “network” and “system”are often used interchangeably. A CDMA network may implement a radiotechnology such as Universal Terrestrial Radio Access (UTRA), cdma2000,etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA.cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network mayimplement a radio technology such as Global System for MobileCommunications (GSM). An OFDMA network may implement a radio technologysuch as new radio (NR) (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra MobileBroadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal MobileTelecommunication System (UMTS).

NR is an emerging wireless communications technology under developmentin conjunction with the 5G Technology Forum (5GTF). 3GPP LTE andLTE-Advanced (LTE-A) are releases of the UMTS that use E-UTRA. UTRA,E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). cdma2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). The techniques describedherein may be used for the wireless networks and radio technologiesmentioned above as well as other wireless networks and radiotechnologies. For clarity, while aspects may be described herein usingterminology commonly associated with 3G and/or 4G wireless technologies,aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

NR access (e.g., 5G technology) may support various wirelesscommunication services, such as enhanced mobile broadband (eMBB)targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW)targeting high carrier frequency (e.g., 25 GHz or beyond), massivemachine type communications MTC (mMTC) targeting non-backward compatibleMTC techniques, and/or mission critical targeting ultra-reliablelow-latency communications (URLLC). These services may include latencyand reliability requirements. These services may also have differenttransmission time intervals (TTI) to meet respective quality of service(QoS) requirements. In addition, these services may co-exist in the samesubframe.

NR supports beamforming and beam direction may be dynamicallyconfigured. Multiple input multiple output (MIMO) transmissions withprecoding may also be supported. MIMO configurations in a downlink (DL)may support up to 8 transmit antennas with multi-layer DL transmissionsup to 8 streams and up to 2 streams per UE. Multi-layer transmissionswith up to 2 streams per UE may be supported. Aggregation of multiplecells may be supported with up to 8 serving cells.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 inwhich aspects of the present disclosure may be performed. For example,the wireless communication network 100 may include one or more basestations (BSs) 110 and/or one or more user equipments (UEs) 120 a-yconfigured for supporting multiple sounding reference signals (SRSs)with a same subframe. As shown in FIG. 1 , a UE 120 a includes a SRSmanager 122 that may be configured to report their capabilityinformation to support multiple SRS transmissions in a single subframein accordance with operations 900 of FIG. 9 . ABS 110 a includes a SRSmanager 112 that may be configured to perform operations 1000 of FIG. 10to configure UEs 120 for the SRS transmissions, based on their reportedcapability information.

The wireless communication network 100 may be a new radio (NR) system(e.g., a 5^(th) generation (5G) NR network). As shown in FIG. 1 , thewireless communication network 100 may be in communication with a corenetwork 132. The core network 132 may in communication with one or moreBSs 110 a-z (each also individually referred to herein as a BS 110 orcollectively as BSs 110) and/or UEs 120 a-y (each also individuallyreferred to herein as a UE 120 or collectively as UEs 120) in thewireless communication network 100 via one or more interfaces.

As illustrated in FIG. 1 , the wireless network 100 may include a numberof BSs 110 and other network entities. A BS 110 may be a station thatcommunicates with UEs 120. Each BS 110 may provide communicationcoverage for a particular geographic area. In 3GPP, the term “cell” canrefer to a coverage area of a Node B (NB) and/or a Node B subsystemserving this coverage area, depending on the context in which the termis used. In NR systems, the term “cell” and next generation NodeB (gNB),NR BS, 5G NB, access point (AP), or transmission reception point (TRP)may be interchangeable. In some examples, a cell may not necessarily bestationary, and the geographic area of the cell may move according tothe location of a mobile BS 110. In some examples, the base stations maybe interconnected to one another and/or to one or more other basestations or network nodes (not shown) in wireless communication network100 through various types of backhaul interfaces, such as a directphysical connection, a wireless connection, a virtual network, or thelike using any suitable transport network.

A BS 110 may provide communication coverage for a macro cell, a picocell, a femto cell, and/or other types of cells. A macro cell may covera relatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs 120 with service subscription.A pico cell may cover a relatively small geographic area and may allowunrestricted access by UEs 120 with service subscription. A femto cellmay cover a relatively small geographic area (e.g., a home) and mayallow restricted access by UEs 120 having an association with the femtocell (e.g., UEs 120 in a Closed Subscriber Group (CSG), UEs 120 forusers in the home, etc.). ABS 110 for a macro cell may be referred to asa macro BS. A BS for a pico cell may be referred to as a pico BS. ABS110 for a femto cell may be referred to as a femto BS or a home BS. Inthe example shown in FIG. 1 , the BSs 110 a, 110 b and 110 c may bemacro BSs for the macro cells 102 a, 102 b and 102 c, respectively. TheBS 110 x may be a pico BS for a pico cell 102 x. The BSs 110 y and 110 zmay be femto BSs for the femto cells 102 y and 102 z, respectively. A BS110 may support one or multiple (e.g., three) cells.

The wireless communication network 100 may also include relay stations.A relay station is a station that receives a transmission of data and/orother information from an upstream station (e.g., a BS 110 or a UE 120)and sends a transmission of the data and/or other information to adownstream station (e.g., a UE 120 or a BS 110). A relay station mayalso be a UE 120 that relays transmissions for other UEs 120. In theexample shown in FIG. 1 , a relay station 110 r may communicate with theBS 110 a and a UE 120 r in order to facilitate communication between theBS 110 a and the UE 120 r. A relay station may also be referred to as arelay BS, a relay, etc.

The wireless communication network 100 may be a heterogeneous networkthat includes BSs 110 of different types, e.g., macro BS, pico BS, femtoBS, relays, etc. These different types of BSs 110 may have differenttransmit power levels, different coverage areas, and different impact oninterference in the wireless communication network 100. For example,macro BS may have a high transmit power level (e.g., 20 Watts) whereaspico BS, femto BS, and relays may have a lower transmit power level(e.g., 1 Watt).

The wireless communication network 100 may support synchronous orasynchronous operation. For synchronous operation, the BSs 110 may havesimilar frame timing, and transmissions from different BSs 110 may beapproximately aligned in time. For asynchronous operation, the BSs 110may have different frame timing, and transmissions from different BSs110 may not be aligned in time. The techniques described herein may beused for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs 110 and providecoordination and control for these BSs 110. The network controller 130may communicate with the BSs 110 via a backhaul. The BSs 110 may alsocommunicate with one another (e.g., directly or indirectly) via wirelessor wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless communication network 100, and each UE 120 may be stationary ormobile. A UE 120 may also be referred to as a mobile station, aterminal, an access terminal, a subscriber unit, a station, a customerpremises equipment (CPE), a cellular phone, a smart phone, a personaldigital assistant (PDA), a wireless modem, a wireless communicationdevice, a handheld device, a laptop computer, a cordless phone, awireless local loop (WLL) station, a tablet computer, a camera, a gamingdevice, a netbook, a smartbook, an ultrabook, an appliance, a medicaldevice or medical equipment, a biometric sensor/device, a wearabledevice such as a smart watch, smart clothing, smart glasses, a smartwrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.),an entertainment device (e.g., a music device, a video device, asatellite radio, etc.), a vehicular component or sensor, a smartmeter/sensor, industrial manufacturing equipment, a global positioningsystem device, or any other suitable device that is configured tocommunicate via a wireless or wired medium. Some UEs 120 may beconsidered machine-type communication (MTC) devices or evolved MTC(eMTC) devices. MTC and eMTC UEs include, for example, robots, drones,remote devices, sensors, meters, monitors, location tags, etc., that maycommunicate with a BS, another device (e.g., remote device), or someother entity. A wireless node may provide, for example, connectivity foror to a network (e.g., a wide area network such as Internet or acellular network) via a wired or wireless communication link. Some UEsmay be considered Internet-of-Things (IoT) devices, which may benarrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequencydivision multiplexing (OFDM) on a downlink (DL) and single-carrierfrequency division multiplexing (SC-FDM) on an uplink (UL). OFDM andSC-FDM partition the system bandwidth into multiple (K) orthogonalsubcarriers, which are also commonly referred to as tones, bins, etc.Each subcarrier may be modulated with data. In general, modulationsymbols are sent in the frequency domain with OFDM and in the timedomain with SC-FDM. The spacing between adjacent subcarriers may befixed, and the total number of subcarriers (K) may be dependent on thesystem bandwidth. For example, the spacing of the subcarriers may be 15kHz and the minimum resource allocation (called a “resource block” (RB))may be 12 subcarriers (or 180 kHz). Consequently, the nominal FastFourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz),respectively. The system bandwidth may also be partitioned intosubbands. For example, a subband may cover 1.08 MHz (i.e., 6 resourceblocks), and there may be 1, 2, 4, 8, or 16 subbands for systembandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR. NR may utilizeOFDM with a CP on the UL and DL and include support for half-duplexoperation using TDD. Beamforming may be supported and beam direction maybe dynamically configured. Multiple input multiple output (MIMO)transmissions with precoding may also be supported. MIMO configurationsin the DL may support up to 8 transmit antennas with multi-layer DLtransmissions up to 8 streams and up to 2 streams per UE. Multi-layertransmissions with up to 2 streams per UE may be supported. Aggregationof multiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a BS 110) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. The scheduling entity may be responsible for scheduling,assigning, reconfiguring, and releasing resources for one or moresubordinate entities. That is, for scheduled communication, subordinateentities utilize resources allocated by the scheduling entity. BSs 110are not the only entities that may function as a scheduling entity. Insome examples, a UE 120 may function as a scheduling entity and mayschedule resources for one or more subordinate entities (e.g., one ormore other UEs 120), and the other UEs 120 may utilize the resourcesscheduled by the UE 120 for wireless communication. In some examples, aUE 120 may function as a scheduling entity in a peer-to-peer (P2P)network, and/or in a mesh network. In a mesh network example, UEs 120may communicate directly with one another in addition to communicatingwith a scheduling entity.

In FIG. 1 , a solid line with double arrows indicates desiredtransmissions between a UE 120 and a serving BS 110, which is a BS 110designated to serve the UE 120 on the DL and/or the UL. A finely dashedline with double arrows indicates interfering transmissions between a UE120 and a BS 110.

FIG. 2 illustrates an example logical architecture of a distributedradio access network (RAN) 200, which may be implemented in the wirelesscommunication network 100 illustrated in FIG. 1 . A 5G access node 206may include an access node controller (ANC) 202. The ANC 202 may be acentral unit (CU) of the distributed RAN 200. A backhaul interface tothe Next Generation Core Network (NG-CN) 204 may terminate at the ANC202. The backhaul interface to neighboring next generation access Nodes(NG-ANs) 210 may terminate at the ANC 202. The ANC 202 may include oneor more TRPs 208 (e.g., cells, BSs, gNBs, etc.).

The TRPs 208 may be a distributed unit (DU). The TRPs 208 may beconnected to a single ANC (e.g., ANC 202) or more than one ANC (notillustrated). For example, for RAN sharing, radio as a service (RaaS),and service specific AND deployments, the TRPs 208 may be connected tomore than one ANC. The TRPs 208 may each include one or more antennaports. The TRPs 208 may be configured to individually (e.g., dynamicselection) or jointly (e.g., joint transmission) serve traffic to a UE.

The logical architecture of the distributed RAN 200 may supportfronthauling solutions across different deployment types. For example,the logical architecture may be based on transmit network capabilities(e.g., bandwidth, latency, and/or jitter).

The logical architecture of the distributed RAN 200 may share featuresand/or components with LTE. For example, next generation access node(NG-AN) 210 may support dual connectivity with NR and may share a commonfronthaul for LTE and NR.

The logical architecture of the distributed RAN 200 may enablecooperation between and among TRPs 208, for example, within a TRP and/oracross TRPs via ANC 202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logicalarchitecture of the distributed RAN 200. As will be described in moredetail with reference to FIG. 5 , a radio resource control (RRC) layer,a packet data convergence protocol (PDCP) layer, a radio link control(RLC) layer, a medium access control (MAC) layer, and a physical (PHY)layers may be adaptably placed at the DU (e.g., TRP 208) or CU (e.g.,ANC 202).

FIG. 3 illustrates an example physical architecture of a distributedradio access network (RAN) 300, according to aspects of the presentdisclosure. A centralized core network unit (C-CU) 302 may host corenetwork functions. The C-CU 302 may be centrally deployed. The C-CU 302functionality may be offloaded (e.g., to advanced wireless services(AWS)), in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions.Optionally, the C-RU 304 may host core network functions locally. TheC-RU 304 may have distributed deployment. The C-RU 304 may be close to anetwork edge.

A DU 306 may host one or more TRPs (edge node (EN), an edge unit (EU), aradio head (RH), a smart radio head (SRH), or the like). The DU 306 maybe located at edges of the network with radio frequency (RF)functionality.

FIG. 4 illustrates example components of a BS 110 and a UE 120 (e.g., inthe wireless communication network 100 of FIG. 1 ).

At the BS 110 a, a transmit processor 420 may receive data from a datasource 412 and control information from a controller/processor 440. Thecontrol information may be for the physical broadcast channel (PBCH),physical control format indicator channel (PCFICH), physical hybrid ARQindicator channel (PHICH), physical downlink control channel (PDCCH),group common PDCCH (GC PDCCH), etc. The data may be for the physicaldownlink shared channel (PDSCH), etc. A medium access control(MAC)-control element (MAC-CE) is a MAC layer communication structurethat may be used for control command exchange between wireless nodes.The MAC-CE may be carried in a shared channel such as a physicaldownlink shared channel (PDSCH), a physical uplink shared channel(PUSCH), or a physical sidelink shared channel (PSSCH).

The transmit processor 420 may process (e.g., encode and symbol map) thedata and control information to obtain data symbols and control symbols,respectively. The processor 420 may also generate reference symbols,e.g., for the primary synchronization signal (PSS), secondarysynchronization signal (SSS), and cell-specific reference signal (CRS).A transmit MIMO processor 430 may perform spatial processing (e.g.,precoding) on the data symbols, the control symbols, and/or thereference symbols, if applicable, and may provide output symbol streamsto modulators (MODs) in transceivers 432 a through 432 t. Each MOD intransceivers 432 may process a respective output symbol stream (e.g.,for OFDM, etc.) to obtain an output sample stream. Each MOD intransceivers 432 may further process (e.g., convert to analog, amplify,filter, and upconvert) the output sample stream to obtain a DL signal.The DL signals from the MODs in transceivers 432 a through 432 t may betransmitted via antennas 434 a through 434 t, respectively.

At the UE 120 a, antennas 452 a through 452 r may receive the DL signalsfrom the BS 110 and may provide received signals to demodulators(DEMODs) in transceivers 454 a through 454 r, respectively. Each DEMODin the transceiver 454 may condition (e.g., filter, amplify,downconvert, and digitize) a respective received signal to obtain inputsamples. Each DEMOD in the transceiver 454 may further process the inputsamples (e.g., for OFDM, etc.) to obtain received symbols. A MIMOdetector 456 may obtain received symbols from all the DEMODs in thetransceivers 454 a through 454 r, perform MIMO detection on the receivedsymbols if applicable, and provide detected symbols. A receive processor458 may process (e.g., demodulate, deinterleave, and decode) thedetected symbols, provide decoded data for the UE 120 to a data sink460, and provide decoded control information to a controller/processor480.

On the UL, at UE 120 a, a transmit processor 464 may receive and processdata (e.g., for the physical uplink shared channel (PUSCH)) transmissionfrom a data source 462 and control information (e.g., for the physicaluplink control channel (PUCCH) from the controller/processor 480. Thetransmit processor 464 may also generate reference symbols for areference signal (e.g., for the sounding reference signal (SRS)). Thesymbols from the transmit processor 464 may be precoded by a transmitMIMO processor 466 if applicable, further processed by the DEMODs intransceivers 454 a through 454 r (e.g., for SC-FDM, etc.), andtransmitted to the BS 110. At the BS 110, the UL signals from the UE 120may be received by the antennas 434, processed by the MOD intransceivers 432, detected by a MIMO detector 436 if applicable, andfurther processed by a receive processor 438 to obtain decoded data andcontrol information sent by the UE 120. The receive processor 438 mayprovide the decoded data to a data sink 439 and the decoded controlinformation to the controller/processor 440.

The memories 442 and 482 may store data and program codes for the BS 110a and the UE 120 a, respectively. A scheduler 444 may schedule UEs fordata transmission on the DL and/or the UL.

Antennas 452, processors 466, 458, 464, and/or controller/processor 480of the UE 120 a and/or antennas 434, processors 420, 430, 438, and/orcontroller/processor 440 of the BS 110 a may be used to perform varioustechniques and methods described herein. For example, as shown in FIG. 4, the controller/processor 440 of the BS 110 a has a SRS manager 441that may be configured to perform the operations illustrated in FIG. 10, as well as other operations disclosed herein. As shown in FIG. 4 , thecontroller/processor 480 of the UE 120 a has a SRS manager 481 that maybe configured to perform the operations illustrated in FIG. 9 , as wellas other operations disclosed herein, in accordance with aspects of thepresent disclosure. Although shown at the controller/processor, othercomponents of the UE 120 a and the BS 110 a may be used performing theoperations described herein.

NR may utilize orthogonal frequency division multiplexing (OFDM) with acyclic prefix (CP) on the uplink and downlink. The NR may supporthalf-duplex operation using time division duplexing (TDD). OFDM andsingle-carrier frequency division multiplexing (SC-FDM) partition thesystem bandwidth into multiple orthogonal subcarriers, which are alsocommonly referred to as tones, bins, etc. Each subcarrier may bemodulated with data. Modulation symbols may be sent in the frequencydomain with OFDM and in the time domain with SC-FDM. The spacing betweenadjacent subcarriers may be fixed, and the total number of subcarriersmay be dependent on the system bandwidth. The minimum resourceallocation, called a resource block (RB), may be 12 consecutivesubcarriers. The system bandwidth may also be partitioned into subbands.For example, a subband may cover multiple RBs. The NR may support a basesubcarrier spacing (SCS) of 15 KHz and other SCS may be defined withrespect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc.).

FIG. 5 illustrates a diagram 500 showing examples for implementing acommunications protocol stack, according to aspects of the presentdisclosure. The illustrated communications protocol stacks may beimplemented by devices operating in a wireless communication system,such as a 5G system (e.g., a system that supports uplink-basedmobility). The diagram 500 illustrates a communications protocol stackincluding a RRC layer 510, a PDCP layer 515, a RLC layer 520, a MAClayer 525, and a PHY layer 530. In various examples, the layers of aprotocol stack may be implemented as separate modules of software,portions of a processor or ASIC, portions of non-collocated devicesconnected by a communications link, or various combinations thereof.Collocated and non-collocated implementations may be used, for example,in a protocol stack for a network access device (e.g., ANs, CUs, and/orDUs) or a UE.

A first option 505-a shows a split implementation of a protocol stack,in which implementation of the protocol stack is split between acentralized network access device (e.g., an ANC 202 in FIG. 2 ) anddistributed network access device (e.g., a DU such as TRP DU 208 in FIG.2 ). In the first option 505-a, an RRC layer 510 and a PDCP layer 515may be implemented by the central unit, and an RLC layer 520, a MAClayer 525, and a PHY layer 530 may be implemented by the DU. In variousexamples the CU and the DU may be collocated or non-collocated. Thefirst option 505-a may be useful in a macro cell, micro cell, or picocell deployment.

A second option 505-b shows a unified implementation of a protocolstack, in which the protocol stack is implemented in a single networkaccess device. In the second option, the RRC layer 510, the PDCP layer515, the RLC layer 520, the MAC layer 525, and the PHY layer 530 mayeach be implemented by the AN. The second option 505-b may be useful in,for example, a femto cell deployment.

Regardless of whether a network access device implements part or all ofa protocol stack, a UE may implement an entire protocol stack as shownin 505-c (e.g., the RRC layer 510, the PDCP layer 515, the RLC layer520, the MAC layer 525, and the PHY layer 530).

In LTE, the basic transmission time interval (TTI) or packet duration isthe 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI isreferred to as a slot. A subframe contains a variable number of slots(e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing.The NR RB is 12 consecutive frequency subcarriers. The NR may support abase subcarrier spacing of 15 KHz and other subcarrier spacing may bedefined with respect to the base subcarrier spacing, for example, 30kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scalewith the subcarrier spacing. The CP length also depends on thesubcarrier spacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. Thetransmission timeline for each of a DL and an UL may be partitioned intounits of radio frames. Each radio frame may have a predeterminedduration (e.g., 10 ms) and may be partitioned into 10 subframes, each of1 ms, with indices of 0 through 9. Each subframe may include a variablenumber of slots depending on the subcarrier spacing. Each slot mayinclude a variable number of symbol periods (e.g., 7 or 14 symbols)depending on the subcarrier spacing. The symbol periods in each slot maybe assigned indices. A sub-slot structure may refer to a transmit timeinterval having a duration less than a slot (e.g., 2, 3, or 4 symbols).Each symbol in a slot may be configured for a link direction (e.g., DL,UL, or flexible) for data transmission and the link direction for eachsubframe may be dynamically switched. The link directions may be basedon the slot format. Each slot may include DL/UL data as well as DL/ULcontrol information.

In NR, a synchronization signal block (SSB) is transmitted. In certainaspects, SSBs may be transmitted in a burst where each SSB in the burstcorresponds to a different beam direction for UE-side beam management(e.g., including beam selection and/or beam refinement). The SSBsincludes a PSS, a SSS, and a two symbol PBCH. The SSB can be transmittedin a fixed slot location, such as the symbols 0-3 as shown in FIG. 6 .The PSS and SSS may be used by UEs for cell search and acquisition. ThePSS may provide half-frame timing, the SS may provide the CP length andframe timing. The PSS and SSS may provide the cell identity. The PBCHcarries some basic system information, such as DL system bandwidth,timing information within radio frame, SS burst set periodicity, systemframe number, etc. The SS blocks may be organized into SS bursts tosupport beam sweeping. Further system information such as, remainingminimum system information (RMSI), system information blocks (SIBs),other system information (OSI) can be transmitted on a PDSCH in certainsubframes. The SSB may be transmitted up to sixty-four times, forexample, with up to sixty-four different beam directions for mmW. Themultiple transmissions of the SSB are referred to as a SS burst set.SSBs in an SS burst set may be transmitted in the same frequency region,while SSBs in different SS bursts sets can be transmitted at differentfrequency regions.

Example SRS Transmissions

In wireless communication systems (e.g., 5^(th) generation (5G) newradio (NR)), a user equipment (UE) (e.g., such as the UE 120 a in thewireless communication network 100) may transmit one or more soundingreference signals (SRSs) so that a network entity (e.g., such as the BS110 a in the wireless communication network 100). can measure uplink(UL) channel quality. Conventionally, one SRS is transmitted by the UEin a last symbol of a normal UL subframe. However, more recently,additional symbols have been introduced for transmitting the SRSs in anormal UL subframe.

The additional SRS symbols may be identified based on a flexible SRSsymbol location configuration and/or a virtual cell ID associated withthe UE that transmitted the (additional) SRSs. In this context, a“normal subframe” is contrasted with a “special subframe” such as thosedefined and placed between “normal downlink (DL) subframes” and “normalUL subframes” that are designed to allow the UE sufficient time toswitch between receive and transmit processing.

Increasing SRS capacity by introducing more than one symbol for the SRSson an UL normal subframe may be part of an overall support of andadvance of coverage enhancements. Increasing the SRS capacity mayinvolve introducing more than one symbol for the SRSs for one UE or formultiple UEs on a UL normal subframe. As a baseline, a minimum SRSresource allocation granularity for a cell may be one slot (e.g., one oftwo time slots of a subframe) or a subframe, when more than one symbolin a normal subframe is allocated for the SRSs for the cell. As notedabove, a virtual cell ID may be introduced for the SRSs, allowingdifferent SRSs transmissions to be distinguished.

Additionally, in some cases, intra-subframe frequency hopping andrepetition may be supported for aperiodic SRSs in the additional SRSsymbols of a normal UL subframe. The intra-subframe frequency hoppingfor the aperiodic SRSs transmission may involve transmitting aperiodicSRSs on different frequency bands on a symbol-by-symbol basis in asubframe. Additionally, the aperiodic SRSs repetition may involverepeating transmission of the aperiodic SRSs, transmitted in a firstadditional symbol of a subframe (e.g., using a first antenna, frequencyband, etc.), in a second additional symbol of the subframe.

Further, intra-subframe antenna switching may be supported for theaperiodic SRSs in the additional SRS symbols. The intra-subframe antennaswitching for the aperiodic SRSs transmission may involve transmittingthe aperiodic SRSs using different antennas on a symbol-by-symbol basisin a subframe.

Both legacy SRS and additional SRS symbol(s) may be configured for thesame UE. In some cases, the legacy SRS may be a periodic SRS (P-SRS) oran aperiodic SRS (A-SRS). Additionally, in some cases, the additionalSRSs may be aperiodically triggered. Currently, the UE may be allowed totransmit periodic legacy SRSs and aperiodic additional SRSs in the samenormal UL subframe. In the case of aperiodic legacy SRS, a UE maytransmit only one of legacy SRS or additional SRS symbol(s) in a normalUL subframe.

The time location of possible additional SRS symbols in one normal ULsubframe for a cell may be selected from various options. According to afirst option, all symbols in only one slot of one subframe may be usedfor the SRSs from the cell perspective. According to a second option,all symbols in one subframe may be used for the SRSs from the cellperspective. In some cases, cell-specific configurations of SRSresources in slot-level granularity may be implemented.

Example Support of Multiple SRS in the Same Subframe

As noted above, in certain wireless communication systems (e.g., In LTERel-16), multiple sounding reference signals (SRSs) transmissions in asingle uplink (UL) subframe may be supported. In contrast, in earlier(legacy) releases of LTE, only a single SRS in a normal UL subframe issupported.

The configuration of multiple SRSs may be quite flexible, allowing forvarious features and enhancements, such as repetition, frequencyhopping, and antenna switching. With the repetition, a SRS istransmitted with a same antenna in contiguous symbols. With thefrequency hopping, the SRS is transmitted in a first bandwidth in afirst symbol and in a second bandwidth in a second symbol. With theantenna switching, the SRS is transmitted from a first antenna in afirst symbol and from a second antenna in a second symbol.

The features, such as the repetition, the frequency hopping, and theantenna switching may be combined for the SRSs transmissions. Oneexample of the SRSs transmissions with the repetition, the frequencyhopping, and the antenna switching is illustrated in FIG. 7 . Forexample, FIG. 7 shows repetition of two (R=2), frequency hopping acrossthree different bandwidths, and antenna switching across two antennas(such as Antenna 1 and Antenna 2).

Another example of the SRSs transmissions with the frequency hopping andthe antenna switching but no repetition is illustrated in FIG. 8 . Forexample, FIG. 8 shows frequency hopping across three differentbandwidths and antenna switching across two antennas (such as Antenna 1and Antenna 2), but without repetition.

Additionally, while not shown in FIG. 7 , gaps (symbols) may beintroduced to allow sufficient time for retuning (for the frequencyhopping) or changing antennas (for the antenna switching). The gaps maybe needed, for example, if a carrier frequency needs to be changed totransmit the one or more SRSs in a different part of a frequency bandwhen hopping frequencies (e.g., the frequency hopping is not digital).These gaps are configurable by a network entity.

The availability of several advanced features and configurable gapsresults in a large number of possible SRS configurations, which presentsa challenge in terms of a user equipment (UE) implementation. Forexample, some configurations that are likely to occur infrequently(corner cases) may be very difficult to implement and, for full support,the UE might have to support these configurations anyway (even when nooperator is likely to support them). Further, it may be practicallyimpossible to test all the possible combinations, especially the fullrange of combinations of the repetition, the antenna switching, thefrequency hopping, and configurable gaps.

Aspects of the present disclosure, however, provide techniques that mayallow a UE, via expanded UE capability signaling, to indicatelimitations that might prevent the UE from supporting all possible SRSsconfiguration combinations.

FIG. 9 is a flow diagram illustrating example operations 900 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 900 may be performed by a UE (e.g.,such as the UE 120 a in the wireless communication network 100) toindicate its capability to support multiple SRS transmissions in asingle subframe and with what advanced features. The operations 900 maybe implemented as software components that are executed and run on oneor more processors (e.g., the controller/processor 480 of FIG. 4 ).Further, the transmission and reception of signals by the UE inoperations 900 may be enabled, for example, by one or more antennas(e.g., the antennas 452 of FIG. 4 ). In certain aspects, thetransmission and/or reception of signals by the UE may be implementedvia a bus interface of one or more processors (e.g., thecontroller/processor 480) obtaining and/or outputting signals.

The operations 900 begin, at 902, by reporting, to a network entity(e.g., such as the BS 110 a in the wireless communication network 100),capability information indicating a capability of the UE to supportmultiple SRSs in a same subframe. The capability information includesone or more parameters indicating capability of the UE to support atleast one of frequency hopping, different bandwidths, or antennaswitching for the multiple SRSs in the same subframe.

At 904, the UE transmits the SRSs to the network entity in accordancewith the capability information. For example, the network entitydetermines an SRS configuration for the UE based on the capabilityinformation of the UE, and configure the UE accordingly. The UE thentransmits the SRSs to the network entity.

FIG. 10 is a flow diagram illustrating example operations 1000 forwireless communications. The operations 1000 may be configuredcomplementary to the operations 900 of FIG. 9 . The operations 1000 maybe performed by a network entity (e.g., such as the BS 110 a in thewireless communication network 100) to configure the UE 120 a 110 a inthe wireless communication network 100 based on its capability tosupport multiple SRSs transmissions in a single subframe (reported inaccordance with operations 900 of FIG. 9 ). The operations 1000 may beimplemented as software components that are executed and run on one ormore processors (e.g., the controller/processor 440 of FIG. 4 ).Further, the transmission and reception of signals by the network entityin operations 1000 may be enabled, for example, by one or more antennas(e.g., the antennas 434 of FIG. 4 ). In certain aspects, thetransmission and/or reception of signals by the network entity may beimplemented via a bus interface of one or more processors (e.g., thecontroller/processor 440) obtaining and/or outputting signals.

The operations 1000 begin, at 1002, by receiving, from a UE, capabilityinformation indicating a capability of the UE to support multiple SRSsin a same subframe. The capability information includes one or moreparameters indicating capability of the UE to support at least one offrequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe.

At 1004, the network entity configures the UE for transmitting the SRSsin accordance with the capability information. The network entitymonitors for the SRSs transmissions sent by the UE, in accordance withthe capability configuration.

In certain aspects, the UE may report various types of parameters to thenetwork entity to indicate the capability information associated withthe UE to support the frequency hopping, the different bandwidths, orthe antenna switching for the multiple SRSs in the same subframe. Theparameters may be reported per band, per band combination, and/or perband of band combination.

In certain aspects, a parameter (that may be reported by the UE to thenetwork entity) may indicate a maximum number of SRS symbols the UEsupports per subframe. The parameter may be useful for the networkentity as one of the potential limitations of the UE is that, whenconfigured with the frequency hopping or the antenna switching, the UEmay need to change power/frequency of the SRSs after every frequency hopor antenna switch. The radio frequency of the UE may not have thecapability to process all these changes (e.g. a limitation of number ofthe frequency hopping or the antenna switching per subframe).

For example, considering an example with 10 symbols and frequencyhopping in different bandwidths in each symbol, the UE may need toadjust transmit power (e.g., power amplifier setting) to match eachfrequency band. The UE radio frequency components may be designed toonly handle a certain number of power levels per subframe, such as 3power levels (which may allow for 2 physical uplink control channel(PUCCH) transmissions with the frequency hopping and 1 for SRS). A gapmay be one symbol (or multiple symbols) long and generally, may not beincluded when counting a number of power changes.

Similarly, repetition generally uses the same power and frequencyresources (and, thus, do not require a power change). Referring back toFIG. 7 , the illustrated example may effectively count as 6 SRS symbols,not 12 (adjusting for the repetition).

For these reasons, when the UE determines what maximum number of SRSsymbols per subframe it is to report, there are various alternatives forconsidering the gaps and/or the repetition. According to a firstalternative, if the UE is configured with the gaps between the SRSsymbols, the gaps are not counted towards a total of the maximum numberof SRS symbols the UE supports per subframe (e.g. 2 antennas+1 gapcounts as 2 symbols). According to a second alternative, the gaps arecounted towards the total (e.g. 2 antennas+1 gap counts as 3 symbols).According to a third alternative, if the repetition is used fortransmitting the SRSs, the repetition is not counted towards the total.According to a fourth alternative, the repetitions are counted towardsthe total.

In some cases, this limitation regarding a maximum number of SRS symbols(and/or other reported limitations) may only apply if the UE isconfigured with the frequency hopping and/or the antenna switching(otherwise any number of SRSs may be supported). Further the limitationregarding a maximum number of SRS symbols (and/or other reportedlimitations) may be reported per band, per band combination, or per bandof band combination.

In certain aspects, a parameter may indicate different number ofantennas (such as transmit antennas and receive antennas) that a UE maysupport for transmitting the multiple SRSs in the same subframe than fora single SRS in the same subframe. In current (legacy) systems, the UEis only able to indicate one capability. For example, in a givenfrequency band in a frequency band combination, the UE reports whetherthe UE supports 1T2R (1 transmit and 2 receive antennas), 1T4R (1transmit and 4 receive antennas), and/or 2T4R (2 transmit and 4 receiveantennas). This antenna switching capability is for a single SRS in anormal UL subframe, and for the SRS in an UL pilot time slot (UpPTS).

Aspects of the present disclosure, however, allow the UE to reportdifferent antenna switching capabilities, for example, to accommodatethe additional complications of multiple SRSs in a normal UL subframe.For example, the UE may report separate capabilities (e.g. per band ofband combination) of the support of different combinations of antennaselection. For example, the UE may support 1T4R with single SRS, butonly 1T2R with multiple SRS.

In certain aspects, a parameter may indicate support of frequencyhopping such as an intra-subframe frequency hopping. This may helpaddress one of the main complications of supporting the frequencyhopping, which depends on whether a UE has to do “analog” or “digital”hopping. In analog frequency hopping, a local oscillator (LO) is tunedto a center of a SRS band. In such cases, after a frequency hop, the LOhas to be retuned (to the center of a new SRS band). In digital hopping,the LO is tuned to the center of a component carrier. In such cases, abaseband processor performs the digital frequency hopping just byplacing data in different subcarriers.

In some cases, the analog frequency hopping may be the only option, forexample, due to issues with the digital frequency hopping. For example,with the digital frequency hopping, “mirror emissions” may appear due toa small allocation being placed far away from the DC subcarrier. Theusage of digital versus analog frequency hopping may depend on a varietyof factors, such as a SRS bandwidth or a particular band of operation(as different bands may have different emission requirements).

In certain aspects, a UE may indicate support of the intra-subframefrequency hopping. For example, the UE may decide to indicate support(or lack of support) for the intra-subframe frequency hopping, dependingon a band (in a band combination), depending on a SRS bandwidth, and/ordepending on a configuration (or not) of gaps in the subframe.

In some cases, the UE can report (for a band of band combination), fordifferent values of bandwidth of SRSs, whether the UE supports frequencyhopping and, if so, whether the UE needs gaps or not. For example, thismay be signaled by zero or more thresholds of bandwidths X_(i) and oneor more indications for support of capabilities Y_(i). One or both ofX_(i) and Y_(i) may be signaled by the UE or fixed in a specification.For example, if X=[4, 10] and Y=[notSupport, supportWithGaps,supportWithoutGaps], this may mean that:

-   -   For less than 4 PRBs of SRS bandwidth, the UE does not support        frequency hopping;    -   For SRS bandwidth between 4 and 10 PRBs, the UE supports        frequency hopping with gaps; and    -   For SRS bandwidth more than 10 PRBs, the UE supports frequency        hopping without gaps.

In some cases, such signaling may be simplified. For example, onesimplification is for the UE to signal two values of X, and the valuesof Y are always assumed to be [notSupport, supportWithGaps,supportWithoutGaps]. In this case, X can include values 0 and 100 (orlarger). As another example of simplification, the support of the gapsby the UE may be signaled by a separate capability. In such cases, theUE may only signal a single threshold X. This may be interpreted asmeaning that if SRS bandwidth is below a first bandwidth threshold, theUE does not support intra-subframe FH, while if the SRS bandwidth isabove a second bandwidth threshold, the UE does support intra-frame FH.The UE may support the intra-subframe frequency hopping without the gapsif the SRS bandwidth is above the second bandwidth threshold. The UE maysupport the intra-subframe frequency hopping with the gaps if the SRSbandwidth is between the first bandwidth threshold and the secondbandwidth threshold.

In certain aspects, the capability information to support the frequencyhopping may depend on a number of repetitions used for the SRSstransmissions.

In certain aspects, the capability information may indicate a number ofsymbols between frequency hops for the UE to support the frequencyhopping without gaps.

In certain aspects, the UE may indicate support of antenna switchingsuch as intra-subframe antenna switching. One potential complication ofthe antenna switching is to program a radio frequency front end toperform the switch in a certain time. In many cases, the radio frequencyhardware (card) may not have the capability to perform very fastswitches (e.g., to switch back to back for many symbols).

In certain aspects, a UE may be able to report, for each frequency bandin a frequency band combination, whether the UE should be configuredwith gaps for antenna switching. This may provide flexibility, forexample, to accommodate when it may be easier for the UE to perform thefrequency hopping and the antenna switching if they are not performedback to back (in adjacent symbols). For example, referring to FIG. 7 ,with repetition (R=2), it may be easier for the UE to perform thefrequency hopping and the antenna switching, than without repetition (asin the example of FIG. 8 ), since the UE has more time to prepare foreach frequency hop and/or antenna switch.

There are various alternatives for the UE to report the support of thefrequency hopping and/or the antenna switching with or without the gaps,and may report different support for different repetition values.

In one example, the frequency hopping and/or the antenna switchingcapabilities may be reported separately, for example, once for R=1 (norepetition) and once for R>1 (with repetition).

In another example, with R>1, a UE may support the frequency hoppingand/or the antenna switching without gaps, and with R=1 the UE mayreport the capability (with gaps).

In another example, a UE may report multiple values of repetition andmultiple capabilities for the frequency hopping, the antenna switching,and/or the gaps corresponding to each of the values of R. As analternative, the UE may report a value of R (as a threshold) and twocapabilities (or sets of capabilities) for the frequency hopping, theantenna switching, and/or the gaps (one for repetitions below R, oneabove R).

In certain aspects, a UE may report a number of symbols the UE should beconfigured with between antenna switches (or frequency hops) to operatewithout gaps. For example, assuming the UE reports N=2 (that the UEshould be configured with at least 2 symbols between consecutive thefrequency hopping and/or the antenna switching), the UE may support afirst two configurations shown in FIG. 11 without gaps, and a thirdconfiguration in FIG. 11 (with a gap between antenna switching). Afourth configuration may not be supported, however, as there is not 2symbols between the antenna switching.

In certain aspects, if a UE performs frequency hopping and antennaswitching in a same symbol, then the UE may be configured with a gap IF(the UE reports that) either frequency hopping or antenna switchingrequires a gap.

In certain aspects, the capability information may indicate whether a UEis able to support different types of SRS in a same subframe. Forexample, legacy SRSs and additional SRSs can be configured in the samesubframe, with potentially different power control parameters. Toaccommodate such cases, the UE may be configured to report whetherlegacy P-SRS and/or AP-SRS can be configured together with theadditional SRSs in the same subframe. If the UE does report that legacyP-SRS and/or AP-SRS can be configured together with the additional SRSsin the same subframe, the UE may also report whether a gap is neededbetween legacy and additional SRSs if different power due to frequencyhopping, antenna switching, and/or power control. As an alternative orin addition, the UE may report whether there is power restrictionbetween power level of legacy SRSs and additional SRSs in the samesubframe.

FIG. 12 illustrates a communications device 1200 that may includevarious components (e.g., corresponding to means-plus-functioncomponents) configured to perform operations for the techniquesdisclosed herein, such as the operations illustrated in FIG. 9 . Thecommunications device 1200 includes a processing system 1202 coupled toa transceiver 1208 (e.g., a transmitter and/or a receiver). Thetransceiver 1208 is configured to transmit and receive signals for thecommunications device 1200 via an antenna 1210, such as the varioussignals as described herein. The processing system 1202 is configured toperform processing functions for the communications device 1200,including processing signals received and/or to be transmitted by thecommunications device 1200.

The processing system 1202 includes a processor 1204 coupled to acomputer-readable medium/memory 1212 via a bus 1206. In certain aspects,the computer-readable medium/memory 1212 is configured to storeinstructions (e.g., a computer-executable code) that when executed bythe processor 1204, cause the processor 1204 to perform the operationsillustrated in FIG. 9 , or other operations for performing the varioustechniques discussed herein. In certain aspects, computer-readablemedium/memory 1212 stores code 1214 for reporting and code 1216 fortransmitting. The code 1214 for reporting may include code forreporting, to a network entity, capability information indicating acapability of the UE to support multiple SRSs in a same subframe wherethe capability information includes one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe. The code 1216 for transmitting may include code fortransmitting the SRSs in accordance with the reported capabilityinformation.

The processor 1204 may include circuitry configured to implement thecode stored in the computer-readable medium/memory 1212, such as forperforming the operations illustrated in FIG. 9 , as well as otheroperations for performing the various techniques discussed herein. Forexample, the processor 1204 includes circuitry 1218 for reporting andcircuitry 1220 for transmitting. The circuitry 1218 for reporting mayinclude circuitry for reporting, to a network entity, capabilityinformation indicating a capability of the UE to support multiple SRSsin a same subframe where the capability information includes one or moreparameters indicating capability of the UE to support at least one offrequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe. The circuitry 1220 for transmittingmay include circuitry for transmitting the SRSs in accordance with thereported capability information.

FIG. 13 illustrates a communications device 1300 that may includevarious components (e.g., corresponding to means-plus-functioncomponents) configured to perform operations for the techniquesdisclosed herein, such as the operations illustrated in FIG. 10 . Thecommunications device 1300 includes a processing system 1302 coupled toa transceiver 1308 (e.g., a transmitter and/or a receiver). Thetransceiver 1308 is configured to transmit and receive signals for thecommunications device 1300 via an antenna 1310, such as the varioussignals as described herein. The processing system 1302 is configured toperform processing functions for the communications device 1300,including processing signals received and/or to be transmitted by thecommunications device 1300.

The processing system 1302 includes a processor 1304 coupled to acomputer-readable medium/memory 1312 via a bus 1306. In certain aspects,the computer-readable medium/memory 1312 is configured to storeinstructions (e.g., a computer-executable code) that when executed bythe processor 1304, cause the processor 1304 to perform the operationsillustrated in FIG. 10 , or other operations for performing the varioustechniques discussed herein. In certain aspects, computer-readablemedium/memory 1312 stores code 1314 for receiving and code 1316 forconfiguring. The code 1314 for receiving may include code for receivingfrom a UE capability information indicating a capability of the UE tosupport multiple SRSs in a same subframe where the capabilityinformation includes one or more parameters indicating capability of theUE to support at least one of frequency hopping, different bandwidths,or antenna switching for the multiple SRSs in the same subframe. Thecode 1316 for configuring may include code for configuring the UE fortransmitting the SRSs in accordance with the reported capabilityinformation.

The processor 1304 may include circuitry configured to implement thecode stored in the computer-readable medium/memory 1312, such as forperforming the operations illustrated in FIG. 10 , as well as otheroperations for performing the various techniques discussed herein. Forexample, the processor 1304 includes circuitry 1318 for receiving andcircuitry 1320 for configuring. The circuitry 1318 for receiving mayinclude circuitry for receiving from a UE capability informationindicating a capability of the UE to support multiple SRSs in a samesubframe where the capability information includes one or moreparameters indicating capability of the UE to support at least one offrequency hopping, different bandwidths, or antenna switching for themultiple SRSs in the same subframe. The circuitry 1320 for configuringmay include circuitry for configuring the UE for transmitting the SRSsin accordance with the reported capability information.

Example Aspects

Implementation examples are described in the following numbered aspects.

In a first aspect, a method for wireless communications by a userequipment (UE), comprising: reporting, to a network entity, capabilityinformation indicating a capability of the UE to support multiplesounding reference signals (SRSs) in a same subframe, wherein thecapability information comprises one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe; and transmitting the SRSs in accordance with thecapability information.

In a second aspect, alone or in combination with the first aspect, atleast one of the one or more parameters are reported per band, per bandcombination, or per band of band combination.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the one or more parameters comprise a maximum numberof SRS symbols the UE supports per subframe, and wherein the maximumnumber of SRS symbols the UE supports per subframe is only applicable ifthe UE is configured with at least one of the antenna switching or thefrequency hopping.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the one or more parameters comprise: anumber of transmit antennas and receive antennas the UE supports fortransmitting multiple SRSs in the same subframe.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, the UE reports support for a different number oftransmit antennas and receive antennas for transmitting multiple SRSs inthe same subframe than for a single SRS in the same subframe.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, the one or more parameters indicate support ofintra-subframe frequency hopping depending on at least one of a band, aband combination, a band of band combination, a SRS bandwidth, or aconfiguration of gaps in the subframe.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the one or more parameters indicate atleast one of: one or more bandwidth thresholds, for which the UEsupports the intra-subframe frequency hopping with or without gaps; afirst bandwidth threshold, wherein the UE does not support theintra-subframe frequency hopping if the SRS bandwidth is below the firstbandwidth threshold; or a second bandwidth threshold, wherein the UEsupports the intra-subframe hopping if the SRS bandwidth is above thesecond bandwidth threshold.

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the UE supports the intra-subframefrequency hopping without the gaps if the SRS bandwidth is above thesecond bandwidth threshold; and the UE supports the intra-subframefrequency hopping with the gaps if the SRS bandwidth is between thefirst bandwidth threshold and the second bandwidth threshold.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, the capability information to support thefrequency hopping depends, at least in part, on a number of repetitionsused for the SRS transmissions.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, the capability information indicates a number ofsymbols between frequency hops for the UE to support the frequencyhopping without gaps.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the one or more parameters comprise: amaximum number of SRS symbols the UE supports per subframe.

In a twelfth aspect, alone or in combination with one or more of thefirst through eleventh aspects, when the UE is configured with gapsbetween SRS symbols, the gaps are not counted towards the maximum numberof SRS symbols the UE supports per subframe.

In a thirteenth aspect, alone or in combination with one or more of thefirst through twelfth aspects, when repetition is used for transmittingthe SRSs, repetitions are not counted towards the maximum number of SRSsymbols the UE supports per subframe.

In a fourteenth aspect, alone or in combination with one or more of thefirst through thirteenth aspects, the one or more parameters indicate,for each band in a band combination, whether the UE is to be configuredwith gaps to support intra-subframe antenna switching, wherein thecapability information to support antenna switching depends, at least inpart, on a number of repetitions used for the SRSs transmissions, andwherein the capability information indicates a number of symbols betweenantenna switches for the UE to support the antenna switching withoutgaps.

In a fifteenth aspect, alone or in combination with one or more of thefirst through fourteenth aspects, when the UE performs frequency hoppingand antenna switching in the same symbol, then a gap is configured ifthe UE indicates it is to be configured with a gap to support eitherfrequency hopping, antenna switching, or both.

In a sixteenth aspect, alone or in combination with one or more of thefirst through fifteenth aspects, the capability information alsoindicates whether the UE is able to support different types of SRS inthe same subframe, and when the capability information indicates UE isable to support different types of SRS in the same subframe, thecapability information also indicates at least one of: whether the UE isto be configured with a gap between SRS of different types due to atleast one of frequency hopping, antenna switching, or power control; orwhether there is a power restriction between power levels of the SRS ofdifferent types.

In a seventeenth aspect, a method for wireless communications by anetwork entity, comprises: receiving, from a user equipment (UE),capability information indicating a capability of the UE to supportmultiple sounding reference signals (SRSs) in a same subframe, whereinthe capability information comprises one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe; and configuring the UE for transmitting the SRSs inaccordance with the capability information.

In an eighteenth aspect, alone or in combination with the seventeenthaspect, at least one of the one or more parameters are reported perband, per band combination, or per band of band combination.

In a nineteenth aspect, alone or in combination with one or more of theseventeenth and eighteenth aspects, the one or more parameters comprise:a maximum number of SRS symbols the UE supports per subframe.

In a twentieth aspect, alone or in combination with one or more of theseventeenth through nineteenth aspects, when the UE is configured withgaps between SRS symbols, the gaps are not counted towards the maximumnumber of SRS symbols the UE supports per subframe.

In a twenty-first aspect, alone or in combination with one or more ofthe seventeenth through twentieth aspects, when repetition is used fortransmitting the SRS, repetitions are not counted towards the maximumnumber of SRS symbols the UE supports per subframe.

In a twenty-second aspect, alone or in combination with one or more ofthe seventeenth through twenty-first aspects, the maximum number of SRSsymbols the UE supports per subframe is only applicable if the UE isconfigured with at least one of the antenna switching or the frequencyhopping.

In a twenty-third aspect, alone or in combination with one or more ofthe seventeenth through twenty-two aspects, the one or more parameterscomprise: a number of transmit antennas and receive antennas the UEsupports for transmitting multiple SRSs in the same subframe.

In a twenty-fourth aspect, alone or in combination with one or more ofthe seventeenth through twenty-third aspects, the UE reports support fora different number of transmit antennas and receive antennas fortransmitting multiple SRS in the same subframe than for a single SRS inthe same subframe.

In a twenty-fifth aspect, alone or in combination with one or more ofthe seventeenth through twenty-fourth aspects, the one or moreparameters indicate support of intra-subframe frequency hoppingdepending on at least one of a band, band combination, band of bandcombination, SRS bandwidth, or configuration of gaps in the subframe.

In a twenty-sixth aspect, alone or in combination with one or more ofthe seventeenth through twenty-fifth aspects, the one or more parametersindicate at least one of: one or more bandwidth thresholds, for whichthe UE supports the intra-subframe frequency hopping with or withoutgaps; a first bandwidth threshold, wherein the UE does not support theintra-subframe frequency hopping if the SRS bandwidth is below the firstbandwidth threshold; or a second bandwidth threshold, wherein the UEsupports the intra-subframe frequency hopping if the SRS bandwidth isabove the second bandwidth threshold.

In a twenty-seventh aspect, alone or in combination with one or more ofthe seventeenth through twenty-sixth aspects, wherein the network entitydetermines that: the UE supports the intra-subframe frequency hoppingwithout the gaps if the SRS bandwidth is above the second bandwidththreshold; and the UE supports the intra-subframe frequency hopping withthe gaps if the SRS bandwidth is between the first bandwidth thresholdand the second bandwidth threshold.

In a twenty-eighth aspect, alone or in combination with one or more ofthe seventeenth through twenty-seventh aspects, the capabilityinformation to support the frequency hopping depends, at least in part,on a number of repetitions used for the SRSs transmissions.

In a twenty-ninth aspect, alone or in combination with one or more ofthe seventeenth through twenty-eighth aspects, the capabilityinformation indicates a number of symbols between frequency hops for theUE to support the frequency hopping without gaps.

In a thirtieth aspect, alone or in combination with one or more of theseventeenth through twenty-ninth aspects, the one or more parametersindicate, for each band in a band combination, whether the UE is to beconfigured with gaps to support intra-subframe antenna switching,wherein the capability information to support antenna switching depends,at least in part, on a number of repetitions used for the SRSstransmissions, and wherein the capability information indicates a numberof symbols between antenna switches for the UE to support antennaswitching without gaps.

In a thirty-first aspect, alone or in combination with one or more ofthe seventeenth through thirtieth aspects, when the UE performsfrequency hopping and antenna switching in the same symbol, then a gapis configured if (when) the UE indicates it is to be configured with agap to support either frequency hopping, antenna switching, or both.

In a thirty-two aspect, alone or in combination with one or more of theseventeenth through thirty-first aspects, the capability informationalso indicates whether the UE is able to support different types of SRSin the same subframe, and wherein, when the capability informationindicates UE is able to support different types of SRS in the samesubframe, the capability information also indicates at least one of:whether the UE is to be configured with a gap between SRS of differenttypes due to at least one of frequency hopping, antenna switching, orpower control; or whether there is a power restriction between powerlevels of the SRS of different types.

An apparatus for wireless communication, comprising at least oneprocessor; and a memory coupled to the at least one processor, thememory comprising code executable by the at least one processor to causethe apparatus to perform the method of any of the first throughthirty-two aspects.

An apparatus comprising means for performing the method of any of thefirst through thirty-two aspects.

A computer readable medium storing computer executable code thereon forwireless communications that, when executed by at least one processor,cause an apparatus to perform the method of any of the first throughthirty-two aspects.

Additional Considerations

The methods disclosed herein comprise one or more steps or actions forachieving the methods. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112(f) unless the element is expressly recited using the phrase“means for” or, in the case of a method claim, the element is recitedusing the phrase “step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering. For example, various operations shown in FIGS. 9 and10 may be performed by various processors shown in FIG. 4 . Moreparticularly, operations 1000 of FIG. 10 may be performed by processors420, 460, 438, and/or controller/processor 440 of the BS 110 shown inFIG. 4 while operations 900 of FIG. 9 may be performed by one or more ofprocessors 466, 458, 464, and/or controller/processor 480 of the UE 120.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userequipment 120 (see FIG. 1 ), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For example, instructions for performing the operationsdescribed herein and illustrated in FIG. 9 and FIG. 10 .

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

The invention claimed is:
 1. A method for wireless communications by auser equipment (UE), comprising: reporting, to a network entity,capability information indicating a capability of the UE to supportmultiple sounding reference signals (SRSs) in a same subframe, whereinthe capability information comprises one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe, and wherein the one or more parameters comprise a numberof SRS symbols the UE supports per subframe; and transmitting the SRSsin accordance with the capability information.
 2. The method of claim 1,wherein at least one of the one or more parameters are reported perband, per band combination, or per band of band combination.
 3. Themethod of claim 1, wherein the number of SRS symbols the UE supports persubframe is only applicable when the UE is configured with at least oneof the antenna switching or the frequency hopping.
 4. The method ofclaim 1, wherein the one or more parameters comprise: a number oftransmit antennas and receive antennas the UE supports for transmittingmultiple SRSs in the same subframe.
 5. The method of claim 4, wherein,the UE reports support for a different number of transmit antennas andreceive antennas for transmitting multiple SRSs in the same subframethan for a single SRS in the same subframe.
 6. The method of claim 1,wherein the one or more parameters indicate support of intra-subframefrequency hopping depending on at least one of a band, a bandcombination, a band of band combination, a SRS bandwidth, or aconfiguration of gaps in the subframe.
 7. The method of claim 6, whereinthe one or more parameters indicate at least one of: one or morebandwidth thresholds, for which the UE supports the intra-subframefrequency hopping with or without gaps; a first bandwidth threshold,wherein the UE does not support the intra-subframe frequency hoppingwhen the SRS bandwidth is below the first bandwidth threshold; or asecond bandwidth threshold, wherein the UE supports the intra-subframehopping when the SRS bandwidth is above the second bandwidth threshold.8. The method of claim 7, wherein: the UE supports the intra-subframefrequency hopping without the gaps when the SRS bandwidth is above thesecond bandwidth threshold; and the UE supports the intra-subframefrequency hopping with the gaps when the SRS bandwidth is between thefirst bandwidth threshold and the second bandwidth threshold.
 9. Themethod of claim 6, wherein the capability information to support thefrequency hopping depends, at least in part, on a number of repetitionsused for the SRS transmissions.
 10. The method of claim 6, wherein thecapability information indicates a number of symbols between frequencyhops for the UE to support the frequency hopping without gaps.
 11. Themethod of claim 1, wherein, when the UE is configured with gaps betweenSRS symbols, the gaps are not counted towards the number of SRS symbolsthe UE supports per subframe.
 12. The method of claim 1, wherein, whenrepetition is used for transmitting the SRSs, repetitions are notcounted towards the number of SRS symbols the UE supports per subframe.13. The method of claim 1, wherein the one or more parameters indicate,for each band in a band combination, whether the UE is to be configuredwith gaps to support intra-subframe antenna switching, wherein thecapability information to support antenna switching depends, at least inpart, on a number of repetitions used for the SRSs transmissions, andwherein the capability information indicates a number of symbols betweenantenna switches for the UE to support the antenna switching withoutgaps.
 14. The method of claim 1, wherein, when the UE performs frequencyhopping and antenna switching in the same symbol, then a gap isconfigured when the UE indicates it is to be configured with a gap tosupport either frequency hopping, antenna switching, or both.
 15. Themethod of claim 1, wherein the capability information also indicateswhether the UE is able to support different types of SRS in the samesubframe, and when the capability information indicates UE is able tosupport different types of SRS in the same subframe, the capabilityinformation also indicates at least one of: whether the UE is to beconfigured with a gap between SRS of different types due to at least oneof frequency hopping, antenna switching, or power control; or whetherthere is a power restriction between power levels of the SRS ofdifferent types.
 16. A method for wireless communications by a networkentity, comprising: receiving, from a user equipment (UE), capabilityinformation indicating a capability of the UE to support multiplesounding reference signals (SRSs) in a same subframe, wherein thecapability information comprises one or more parameters indicatingcapability of the UE to support at least one of frequency hopping,different bandwidths, or antenna switching for the multiple SRSs in thesame subframe, and wherein the one or more parameters comprise a numberof SRS symbols the UE supports per subframe; and configuring the UE fortransmitting the SRSs in accordance with the capability information. 17.The method of claim 16, wherein at least one of the one or moreparameters are reported per band, per band combination, or per band ofband combination.
 18. The method of claim 16, wherein, when the UE isconfigured with gaps between SRS symbols, the gaps are not countedtowards the number of SRS symbols the UE supports per subframe.
 19. Themethod of claim 16, wherein, when repetition is used for transmittingthe SRS, repetitions are not counted towards the number of SRS symbolsthe UE supports per subframe.
 20. The method of claim 16, wherein thenumber of SRS symbols the UE supports per subframe is only applicablewhen the UE is configured with at least one of the antenna switching orthe frequency hopping.
 21. The method of claim 16, wherein the one ormore parameters comprise: a number of transmit antennas and receiveantennas the UE supports for transmitting multiple SRSs in the samesubframe.
 22. The method of claim 21, wherein, the UE reports supportfor a different number of transmit antennas and receive antennas fortransmitting multiple SRS in the same subframe than for a single SRS inthe same subframe.
 23. The method of claim 21, wherein the one or moreparameters indicate support of intra-subframe frequency hoppingdepending on at least one of a band, band combination, band of bandcombination, SRS bandwidth, or configuration of gaps in the subframe.24. The method of claim 23, wherein the one or more parameters indicateat least one of: one or more bandwidth thresholds, for which the UEsupports the intra-subframe frequency hopping with or without gaps; afirst bandwidth threshold, wherein the UE does not support theintra-subframe frequency hopping when the SRS bandwidth is below thefirst bandwidth threshold; or a second bandwidth threshold, wherein theUE supports the intra-subframe frequency hopping when the SRS bandwidthis above the second bandwidth threshold.
 25. The method of claim 24,wherein the network entity determines that: the UE supports theintra-subframe frequency hopping without the gaps when the SRS bandwidthis above the second bandwidth threshold; and the UE supports theintra-subframe frequency hopping with the gaps when the SRS bandwidth isbetween the first bandwidth threshold and the second bandwidththreshold.
 26. The method of claim 23, wherein the capabilityinformation to support the frequency hopping depends, at least in part,on a number of repetitions used for the SRSs transmissions.
 27. Themethod of claim 23, wherein the capability information indicates anumber of symbols between frequency hops for the UE to support thefrequency hopping without gaps.
 28. The method of claim 16, wherein theone or more parameters indicate, for each band in a band combination,whether the UE is to be configured with gaps to support intra-subframeantenna switching, wherein the capability information to support antennaswitching depends, at least in part, on a number of repetitions used forthe SRSs transmissions, and wherein the capability information indicatesa number of symbols between antenna switches for the UE to supportantenna switching without gaps.
 29. The method of claim 16, wherein,when the UE performs frequency hopping and antenna switching in the samesymbol, then a gap is configured when the UE indicates it is to beconfigured with a gap to support either frequency hopping, antennaswitching, or both.
 30. The method of claim 16, wherein the capabilityinformation also indicates whether the UE is able to support differenttypes of SRS in the same subframe, and wherein, when the capabilityinformation indicates UE is able to support different types of SRS inthe same subframe, the capability information also indicates at leastone of: whether the UE is to be configured with a gap between SRS ofdifferent types due to at least one of frequency hopping, antennaswitching, or power control; or whether there is a power restrictionbetween power levels of the SRS of different types.
 31. An apparatus forwireless communications by a user equipment (UE), comprising: a memorycomprising computer-executable instructions; and a processor configuredto execute the computer-executable instructions and cause the UE to:report, to a network entity, capability information indicating acapability of the UE to support multiple sounding reference signals(SRSs) in a same subframe, wherein the capability information includesone or more parameters indicating capability of the UE to support atleast one of frequency hopping, different bandwidths, or antennaswitching for the multiple SRSs in the same subframe, and wherein theone or more parameters comprise a number of SRS symbols the UE supportsper subframe; and transmit the SRSs in accordance with the capabilityinformation.
 32. An apparatus for wireless communications by a networkentity, comprising: a memory comprising computer-executableinstructions; and a processor configured to execute thecomputer-executable instructions and cause the network entity to:receive, from a user equipment (UE), capability information indicating acapability of the UE to support multiple sounding reference signals(SRSs) in a same subframe, wherein the capability information includesone or more parameters indicating capability of the UE to support atleast one of frequency hopping, different bandwidths, or antennaswitching for the multiple SRSs in the same subframe, and wherein theone or more parameters comprise a number of SRS symbols the UE supportsper subframe; and configure the UE for transmitting the SRSs inaccordance with the capability information.